Ireland has voted No to the Lisbon Treaty, plunging the European Union into a new crisis.

With results coming in from across the country, a final result of 52 per cent against and 48 per cent in favour of the treaty was rapidly hardening. A final declaration is not expected until after 4 pm.

The Lisbon Treaty, the reworked successor to the formal constitutional pact dumped by voters in France and the Netherlands in 2005, officially needs the approval of all 27 EU member states. But only in Ireland has it been put to a popular vote, meaning today's result may have far-reaching consequences for the entire bloc.

Barely two hours after the count began today, the No camp had already started celebrating, while senior Fianna Fail strategists privately and glumly conceded their defeat.

“Call it hubris,” said one senior figure, “people seem to have forgotten what Ireland was like before we received European funding. They seem to think that we created our success all by ourselves. They are wrong.”

The senior figure admitted that in spite of Brian Cowen’s assurance on the eve of voting that a rerun – as happened after the Irish rejected the Nice treaty in 2001 – would not occur, it was now much more likely.

“The other 26 countries will ratify and we will be told ‘Join us when you like lads’,” he said.

In a television interview last night, Francois Fillon, French Prime Minister, was clear about the effects of a No vote. “If the Irish people decide to reject the treaty of Lisbon, naturally, there will be no treaty of Lisbon,” he warned.

Commentators said that would be a disaster for Mr Cowen, the newly appointed Irish Prime Minister who has struggled to rally the Yes vote following a surprise last-minute surge in opinion poll support for the 'no' campaign in the past week.

The final turnout figure was not yet clear. Commentators and pundits had said that a low figure would help the No campaign, since their supporters were more committed and likely to cast their ballots.

Ireland's rejection of the Lisbon Treaty leaves the EU — whose leaders meet for a summit in Brussels next week — facing a new crisis like that which followed the 2005 rejection of the formal constitution. It also means that three million voters have effectively decided the fate of a bloc of almost 500 million people.

Ireland has caused upsets in EU referendums before. In 2001, its voters rejected the Nice Treaty, a result overturned in a second poll the following year.

Backers of the treaty, which aims to make EU decision-making more efficient, struggled to get their message across, despite a campaign backed by all bar one of the main political parties.

With many Irish people complaining that they do not understand what the treaty is about, pre-referendum opinion polls placed the Yes and No camps virtually neck-and-neck.

One opinion poll last week put the No campaign ahead on 35 per cent, compared to 30 percent for those backing the treaty, while another survey Sunday predicted a narrow Yes victory, by 42 to 39 per cent.

Opponents rallied support for the No campaign around claims including that the treaty threatens sensitive Irish policies like the ban on abortion, low corporation tax and military neutrality. Elsewhere in Europe there has been some bemusement that a country which owes its economic success - as the Celtic Tiger of the 1990s - largely to massive European Union investment should reject closer European ties.

Libertas, a group run by the businessman Declan Ganley and the Sinn Fein party, led by Gerry Adams, were among the most prominent 'no' campaigners.

Mr Ganley said today that the results coming in were very encouraging.

"The Irish people should never have been taken for granted. In their enormous wisdom they have taken on board the treaty, looked at the arguments and, it seems that we have returned the same result again that our fellow Europeans in France and the Netherlands have already sent to the unelected Brussels elite."

He added: "In fairnesss to Mr Cowen and the Yes side they did everything they could - including some off-the-ball tackles - to get the result that Brussels wanted, so nobody should criticised him from there.

"But what this does is to give Mr Cowen a mandate to go back to Brussels and build a better deal. I have faith in him that he will do that."

In a sign of the passions aroused by the issue, Brian Lenihan, the Finance Minister, had to be escorted from Dublin's main counting station when No campaigners attempted to drown him out and scuffles broke out. "As you know from Eastern Europe when the Far Right and the Far Left take over free speech disappears very fast," he said.

Mr Lenihan told The Times: "The trend is not favourable. I am disappointed with the result. Clearly Ireland is not in a position to ratify the treaty.

"We will await the reaction of other member states."

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